Thermoplastic resin films which have satisfactory water resistance, in particular, polyolefin-based synthetic papers, may be used, for example, as stickers for outdoor advertising or as labels which may be applied to containers for frozen foods, because the conventional stickers, and the coated paper used in such labels, have poor water resistance.
Resin films for use in water resistant labels are known. With respect to details thereof, reference may be made to, for example, such films are described in Examined Japanese Patent Publications Nos. 46-40794 and 49-1782, Unexamined Published Japanese Patent Applications Nos. 56-118437, 57-12642, and 57-56224, etc.
However, such polyolefin-based synthetic papers, when used as labels and printed with a heated-roll fixing type electrophotographic printer, in which the heated roll has a surface treatment as high as 140 to 190° C., have a higher degree of thermal shrinkage than the release paper adhered thereto, which causes the label to curling considerably after printing. In extreme cases, the label paper may roll up into a cylinder, making it difficult to peel the printed synthetic paper from the release paper. Because of this curling problem, polyolefin-based synthetic papers cannot be satisfactorily printed using a heated-roll fixing type electrophotographic printer.
An object of the present invention is to provide a thermoplastic resin film, and a label papers comprising such a film, which has reduced thermal curling compared with conventional papers, and can be easily peeled from the release paper when used as a label printed with a heated-roll fixing type electrophotographic printer.